TRAF4-SMURF2-mediated DAZAP2 degradation is critical for IL-25 signaling and allergic airway inflammation.

Jarod A Zepp, Ling Wu, Wen Qian, Wenjun Ouyang, Mark Aronica, Serpil Erzurum, Xiaoxia Li

Index: J. Immunol. 194(6) , 2826-37, (2015)

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Abstract

IL-25 promotes type 2 immunity by inducing the expression of Th2-associated cytokines. Although it is known that the IL-25R (IL-17RB) recruits the adaptor protein ACT1, the IL-25R signaling mechanism remains poorly understood. While screening for IL-25R components, we found that IL-25 responses were impaired in Traf4 (-/-) cells. Administering IL-25 to Traf4 (-/-) mice resulted in blunted airway eosinophilia and Th2 cytokine production. Notably, IL-25R recruitment of TRAF4 was required for the ACT1/IL-25R interaction. Mechanistically, TRAF4 recruited the E3-ligase SMURF2, to degrade the IL-25R-inhibitory molecule DAZAP2. Silencing Dazap2 increased ACT1/IL-25R interaction and IL-25 responsiveness. Moreover, a tyrosine within the IL-25R elicited DAZAP2 interference. This study indicates that TRAF4-SMURF2-mediated DAZAP2 degradation is a crucial initiating event for the IL-25 response. Copyright © 2015 by The American Association of Immunologists, Inc.